Telephone system



C. E. LOMAX TELEPHONE SYSTEM Dec. 31, 1940.

5 Sheets-Sheet 1 Filed April 28, 1939- QQQE m 5 \WQEQWQ mgovk INVENTOR.

CLARENCE E. LOMAX AT ORNEYE 3 1940- .c. E. LOMAX TELEP\HONE SYSTEM Filed April 28, 1959 5 Sheets-Sheet 2 CLARENCE E. LOMAX BY M m ATTORNEYfi Patented Dee. 31, 1940 PATENT OFFICE TELEPHONE SYSTEM Clarence E. Lomax, Oak Park, 111., assigns: to Associated Electric Laboratories, Inc., Chicago, Ill., a corporation of Delaware Application April 28, 1939, Serial No. 270,539

22 Claims.

The present invention relates to telephone systems and, more particularly, to improved apparatus-for controlling the collecting and refunding of coins deposited in the coin-receiving means of pay stations forming a part of an automatic telephone system.

In the usual automatic telephone system, a portion of the substations are of the paystation type, each including means for receiving coins,

w slugs, or the like, and a coin control mechanism for controlling the coin refunding and collecting operations normally required incident to use of the station. Accordingly, the automatic switching apparatus of the system must be suitably arranged automatically to control the pay station coin control mechanisms incident to the use of local connections involving the paystations and must include apparatus for permitting operators selectively to control the mechanisms so that the proper charges and collections may be made incident to the use of toll connections involving the paystations. Prior automatic telephone systems including these paystation control features are more or less complicated in arrangement and include a large amount of equipment which is used only for the purpose of effecting proper control of the coin mechanisms provided at the paystations. For example, complicated and specially designed intermediate and final selector switches are usually provided for enabling toll operators to set up delayed callconnections to the paystations and for permitting the proper coin collecting and refunding operations to be made. In the usual arrangement these special'switches are used only in setting up toll call connections. Moreover, prior paystation trunk circuits, in general, require a large amount of relay equipment for effecting the proper control of the paystation coin control mechanisms.

It is an object of the present invention to provide, in an automatic telephone system, improved and exceedingly simple apparatus for controlling the coin collecting and refunding operations required incident to the use of connections involving the paystations embodied in the system.

It is another object of the invention to provide, in an automatic telephone system, improved and simplified apparatus whereby an operator can control the collecting and refunding of coins deposited at the paystations of the system at which calls originate or to which calls are routed.

It is a further object of the invention to provide improved apparatus of the character described which is so arranged that the regular automatic switching apparatus of the system may be used in completing both local and toll connections without sacrificing any of the required paystation control features.

It is a still further object of the invention to provide improved and exceedingly simple pay- 5 station circuit apparatus adapted for use in con- Junction with the individual paystation lines which is so arranged that all required paystation control operations are effected with a mini- -mum amount of equipment. r

It is a further and more specific object of the invention to provide improved paystation control apparatus of the character described wherein booster battery control is utilized in effecting coin refunding and coin collecting operations. I

In the illustrated embodiment of the invention there is disclosed an automatic telephone system which includes a plurality of lines, one of which extends to a substation of the paystation type, together with automatic switching apparatus including a group of final selector switches, which apparatus is operative to establish connections between the various lines. There is also embodied in the system an operator's position to which toll calls may be routed from the substation lines and by way of which calls may be routed to the substation lines. The above-mentioned paystation comprises means for receiving coins, slugs, or the like and means for controlling the collecting and refunding of coins deposited in the coin-receiving means. In accordance with one feature of the present invention, paystation control apparatus is embodied in each of the group of final selector switches mentioned above," which apparatus is, in each case, controllable from the operator's position to control the coin refunding and collecting control means provided at the paystation only for the purpose of causing coins deposited in the coin-receiving means to be refunded. This apparatus in no way prevents the switches from being utilized in completing local call connections. On the contrary, the arrange ment is such that these switches may be utilized in extending calls to and from the operator's position on calls involving any of the substations of the system and in setting up 'local call connections between any of the lines of the system. More particularly, this apparatus as embodied in each switch is operative in response to an unbalanced condition of an established loop circuit extending to the corresponding switch to cause the above-mentioned coin refunding and collecting control means immediately to operate to refund coins deposltedin the coin-receiving means.

The above-described coin control apparatus is primarily utilized in controlling the coin collecting and refunding control means to make coin refunds on calls routed from the operator's posi- 8 tion to the above-mentioned paystation. In regard to the collection of deposited coins, each of the paystation lines has associated therewith a paystation control circuit which functions, on toll calls routed to and from the operator's position,

10 only to control the coin refunding and collecting control means provided at the associated paystation in its operation to effect a coin collecting operation. These paystation control circuits, on local calls originating at the associated paystations, are arranged to operate ina novel manner to cause both coin refunding and collecting operations to be performed: Two embodiments of this improved control circuit are disclosed. In one embodiment, reverse battery control is utilized and in the other embodiment the arrangement is such that booster battery control may be utilized.

Further features of the invention pertain to the particular arrangement of the various 2:; switching elements, whereby the same switches may be used in completing both local and toll connections, and the required apparatus for effecting control of the coin refunding and collecting control means is reduced to a minimum.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, together with-further objects and advantages thereof, will best be understood by reference to the specification taken in connection with the accompanying drawings, "in which Figures 1 to 5, inclusive, when combined in the manner shown in Fig. 7,-illustrate a telephone sys- 0 tem having incorporated therein the features of the invention as briefly outlined above; and Fig. 6 illustrates a modification of certain of the apparatus shown in Fig. 1. I

In general, the system, as illustratedin Figs.

l to 6, inclusive, of the drawings, comprises a relatively small community automatic exchange and a second central exchange, the two exchanges being interconnected by a plurality of two-way trunk lines, one of. which is indicated at It in-Fig. 5 as extending to an operators position I9 provided in the central exchange. In the particular arrangement shown, the community automatic exchange is designed to serve one hundred lines or less. Two of these lines are as indicated at I I and I 2 as extending respectively to the substations A and B, the substation A being of the paystation type and the substation B being of the conventional common battery type of which there are several well-known commergo cial embodiments. The line I2 and the other similar lines may be of the single party type or of the multiparty type, as desired. For the purpose of setting up connections between the lines terminating at the community exchange, as there is provided automatic switching equipment which comprises a plurality of finder-connector links, one of which is illustrated as comprising a finder switch I4 and the connector switch shown in Figs. 2 and 3 of the drawings.

70 For the purpose of assigning idle ones of the finder connector switch to the use of calling lines in a definite order there is provided a distributor I5. Each of the regular subscribers lines of the system terminates in the community ex- 75 change in a line circuit of conventional arrangement, umassociated with the 1...... being in dicated at I. The finder and connector switches each have access to all of the lines terminating at the community exchange and also to repeatera individually associated with the trunk lines 5 extending to the central oiiice. Thus. the connector switch shown in Figs. 2 and 3 has access by way of a link line It to a two-way-repeater II associated with the two-way trunk line II. Calls routed from the central exchange over the 10 trunk line I. and intended for a subscriber's line terminating in the community exchange may be routed through the repeater II and any one of the finder-connector links provided in the community exchange to the desired subscriber's 15 line. To this end, there is associated with the link line I I a line circuit II of conventional arrangement.

Any desired number of the subscribers lines terminating at the community exchange may be 20 arranged to serve substations of the paystation type and such substations may each be of the form illustrated in Fig. 1 forthesubstation A. In brief, the apparatus provided at this substation comprises a transmitter I", a receiver III is and an induction coil I02 arranged to be interconnected through operation of a hook switch I03 to form a substation circuit of the wellknown anti-side-tone type. For the purpose of audibly indicating the presence of incoming calls 30 on the line II, there is also provided at the sub station A a signal device in the form of a ringer I 08 which is bridged across the conductors II and II of the line II in series with a condenser I05. In order to transmit switch control im- 5 pulses by way of thellne II to the automatic switching equipment provided in the line terminating exchange, there is embodied in the substation apparatus a calling or impulsing device I". The substation further comprises coinso receiving means, not shown, which includes a coin depositv chute, a coin collect chute and a coin refund chute, together with apparatus for selectively directing a deposited coin into the correct one of the coin collect and coin refund 45 chutes. This apparatus includes a coin-directing door, not shown, which is arranged to be operated by a polarized electromagnetic device It" having windings adapted to be connected between the line conductors II. and ground in to series with a glow discharge device in the form of a neon tube I. The electromagnetic device III'I is so arranged that when its windings are energized by current of one polarity the associated coin-directing door is rocked in one direction todirect depositedcoins into the coin collect chute and when its windings are energized by current of the opposite polarity the associated'coin-directing door is rocked in another direction to direct deposited coins into the coinm) refund chute. The neon tube III has the wellknown characteristic of being non-conductive until apredetermined voltage is impressed across the terminals thereof. Following ionization of the gas contained therein the voltage required to maintain the tube conductive is substantially less than that required for initiating ionization. Also, the resistance of the device is substantially lessened after the device is rendered conduc tive. The series circuit including the tube Ill-:0 and the windings of the device I" also includes a pair of contact springs I I! which are only operated into engagement in response to the deposit of a coin in the coin deposit chute of the coin-receiving means. When once operated 7s into engagement, the springs I03 are not disengaged until the electromagnetic device I01 opcrates in one manner or the other. The coin collect apparatus provided'at the .substation A and schematically shown in Fig. 1 of the drawings may be of the well-known type shown and described in Patent No. 1,043,219, granted November 5, 1912, Fosberg, although preferably this apparatus and the impulsing device I04 of the substation are arranged inthe manner disclosed and claimed in copending application Serial No. 265,459, flied April 1, 1939, Clarence E. Lomax. As thus arranged, certain calls, such, for example, as trunk calls to an operator's positionin the distant central omce, may successfully be completed without-thedeposit of a coin in the coin-receiving means, whereas other calls intended for the substations local to the com.- munity exchange can only successfully be completed after a coin has been deposited in the coin-receiving means. To this end, and as disclosed in the aforementioned copending application, the substation circuit is so arranged that only a predetermined number of digits, as, for example, two digits, may effectively be transmitted from the substation, a digit counter being provided for shunting the pulsing springs of this device after a predetermined number of digits has been dialed.

For the purpose of controlling the coin collecting and coin refunding operations required incident to the use of connections resulting from calls originating at the substation A, the line H is divided into two parts which are connected by a combined paystation control and line circult I'I. This trunk circuit comprises a coin control and line switching relay R120 arranged to be controlled by a pair of additional relays RIM and Rl00, the first of which is of the slowto-release type. The relay Ri50 also functions in the capacity of a cut-ofi relay. The circuit ll furtherincludes a slow-to-release line relay RIM and an electro-polarized relay Ri30 which functions to determine whether a coin refund or. coin collect operation is to be performed incident to operation of the relay Rl20. This polarized relay comprises an upper winding serially included in one side of the line II and shunted by a resistor I32 for by-passing voice frequency currents. This relay is so constructed and arranged that it only operates when its lower winding is polarized and current of a predetermined polarity is directed through its upper winding. When once operated, however, the relay Rl30 remains operated so long as its lower winding is energized and regardless of the polarity of the current traversing its upper winding. Several embodiments of this type of relay are commercially available.

On a call originating at a paystation, such, for example, as the station A, and routed to an operator's position in the central ofiice, it is necessary that apparatus be provided for disclosing to the operator the identity of the calling station in order that the proper charges may be assessed and the proper collection made. For this purpose there is provided a tone generator 2| which is arranged to impress its alternating voltage output upon the control conductor I Id of the line it through a condenser 22.

Each of the finder switches embodied in the automatic switching apparatus provided in the community exchange is preferably of the' wellknown Strowger type of which several commercial embodiments are known. The distributor I! may be of any desired commercial construction. The connector switches of this exchange are all of identical arrangement. In brief, the connector switch shown in Figs. 2 and 3 comprises a plurality of bank contactsarranged in levels; a wiper carriage structure including the wipers 30] to 384, inclusive; means comprising a vertical magnet 243 for elevating the wiper carriage structure to bring the wipers opposite a desired level of contacts; means comprising a rotary magnet 342 for rotating the indicated wipers until they engage a desired set of contacts in a selected level; a release magnet 22]; three sets of ofl-normal springs 203, 224 and 245; and a plurality of control relays connected and arranged in the manner illustrated. More particularly, the control relays of the connector switch include a line switching relay R200 of the slow-to-release type, a called party answer or back-bridge relay R2i0, a line relay R230, 9. slow-to-release hold relay R235, a slow-to-release digit transfer relay R240, a slow-acting ring cutoil relay R250, a ringing control relay R260, a pair of boosterbattery control relays R290 and R295, a busy test relay R300, a pair of slow-torelease pulse responsive relays R310 and R320, and a slow-to-operate line switching relay R330. The slow-acting relay R320 is arranged to cooperate with a trunk hunting relay R325 to control the operation of the wipers 3N to 300, inclusive, when the connector switch is functioning to search for an idle one of the trunk lines extending to the central omce. The control apparatus of the connector switch further includes three additional relays R225, R340 and R345 which are provided for the purpose of controlling coin refunding operations performed incident to the completion of calls routed from an operators position in the central oifice to, the

paystation llnesterminating at the community exchange. In order to transmit paystation tone voltage impressed upon the control conductor 20 of the trunk line 20 incoming to the connector switch to the control conductor of a link line extending to one of the repeaters selected through operation of the connector switch, there is also embodied in the connector switch a signal voltage repeating transformer MB.

The connector switch is arranged to provide selective code ringing of the substations associated with the multi-party subscribers lines of the system. To this end there is embodied in the connector switch an impulse responsive code selecting switch 350 of the well-known minor type. In brief, this code selecting switch comprises two sets of bank contacts 35! and 352 of eleven points each; wipers 353 and 350 indi-' vidually associated'with the contact sets; means comprising an operating magnet 356 and a ratchet and pawl mechanism, not shown, for stepping the wipers over the contacts of their respective trunk line i0 extending between the community exchange and the central oillce comprises a re- 1 peating transformer 520 and a plurality of relays for controlling the signaling and line switching operations required incident to the extension of connections in either direction through the repeater. More particularly, the relay equipment of this repeater comprises a line relay R400, a

slow-to-release hold relay RAM, a ringing relay- R420, a ring cut-'ofl'relay R430, and a pair of 4 i 1 relays R440 and R450 which function to control the transmission of the paystation tone signal voltage over the trunk line II to the operator's positio IS. The relay R440 is of the slow-tooperate type and the relay R450 is of the wellknown pendulum type. The relays Just described are utilized primarily in the extension of lay R530, a back-bridge relay R550, a slow-act ing line switching relay R510, and a control relay R550. Two additional relays R540 and R450 are embodied in the repeater II for the purpose of controlling coin refunding operations required incident to the use of paystations associated with the paystation lines terminating at the community exchange. For the purpose of transmitting paystation tone signals over the trunk line i0,

- there is embodied in the repeater a transformer 405 which includes a primary winding 400, bridged between the control conductor I3e of the link line I3 and ground, and a secondary winding 461 which is adapted to be bridged across the line conductors of the repeater in series with a condenser 450.

The trunk line I terminates in the central exchange in a repeater transformer 500, one side of which is connected to the tip and ring contacts of a call and answer jack 50i located at the operator's position i0. The apparatus provided at the operator's position It also includes a signal device in the form of a drop 502 which includes a winding normally bridged between ground and the junction point of the secondary windings of the transformer 500 in series with a condenser 503. For the purpose of transmitting switch control impulses from the operator's position I9 over the trunk line l0 to the repeater I8, there is provided a calling or impulsing device 504. The apparatus provided at this operator's position further includes a coin refunding control key 505 of the nonlocking type which is operative to impress the positive potential of a booster battery current source 5 upon a simplex circuit including the trunk line I0, thereby to control the two relays R540 and R460 embodied in the repeater I8. The apparatus provided at the operator's position I9 also includes an operator's cord circuit, not shown, which may be of any desired commercial arrangement.

As explained above, the arrangement of the apparatus provided at each of the substations of the paystation type is such that a local call initiated at any one of these substations can only be completed if the correct coin deposit is made in the coin-receiving means provided at the calling substation. Assuming, for example, that a party at the substation A desires a connection with the substation B, the call is initiated in the usual manner by removing the receiver IOI from the supporting hook II4 of the hook switch I03. In response to this operation a loop circuit is completed over which the line relay RI is energized. This loop circuit extends from battery by way of the winding of RIGO,

-RAI5I, RAI2I, the line conductor lit, the,pulshook I" and associated contacts H5 and 0, the induction coil winding 2, the line conductor b. RAI22, the upper winding of RI30 and RAI52 to ground. when the hook switch I03 is operated to its oil-normal position the contact springs II3 are also closed so that the induction coil I02, the transmitter I00 and the receiver i0I are properly interconnected for the reception and transmission of voice frequency currents. The line relay RI 00 responds to the completion of the above-traced loop circuit by operating to .complete, at RAIII. a path extending through the winding of the cut-oil relay Bill for marking the line II in the bank contacts of the finder switches having access thereto. At RAII2, the relay RI completes a path including RAI55 for impressing ground potential upon the distributor start conducton C163. The distributor i5 responds to the last-mentioned operation by mitiating the operation of an idle one of the finder switches to search for the calling line. Assuming, for example, that the link comprising the finder switch i4 is assigned bythe distributor I5 to the use of the line II, this switch operates in a well-known manner to seize the line II, as marked in the bank contacts of the finder switch l4 over the above-traced marking path, and to extend the calling loop circuit to the connector switch shown in Figs. 2 and 3. The line relay R230 is energized over this loop circuit and operates. More particularly, the circuit for energizing the line relay R230 may be traced as extending from ground by way of RA242, the lower winding 0! R230, the lower winding of R225,-

erates to complete, at RA23I, a circuit extend-.

ing from ground at RA205 for energizing the winding of R235 in series with the upper winding of the relay R240. The relay R235, upon operating, prepares, at RA231, various circuits, traced hereinafter, for energizing, certain of the other relays shown in Figs. 2 and 3. At RA230, the relay R235 opens a point in the circuits, traced hereinafter, for energizing the release magnets 221 and 351. At RA230, the relay R235 also prepares pulsing circuits, traced hereinafter, for respectively energizingv the vertical magnet 245, the rotary magnet 342 and the operating magnet 356 of the minor switch 350. The relay R240, upon operating, prepares, at RA243, a holding circuit for itself and prepares, at RA244, the above-mentioned circuit for energizing the vertical magnet 240. At M2 and RA242, the relay R240 substitutes ground through the secondary winding of the transformer 241 for: ground derived from the contact associated with RA242 in the above-traced loop circuit including the two. windings of the line relay R230. When the secondary winding of the transformer 241 is included in this loop circuit, the usual dial tone signal is transmitted through the transformer 241 to the receiver "I provided in the calling substation.

At RA230, the hold relay R235, upon operatas extending by way of the grounded conductor ing, impresses ground potential upon the control conductor 2% of the trunk line 20. This ground is extended to the private conductor Ha of the calling line H through the finder switch i4. When ground potential is impressed upon the indicated control conductor, the relay RIM is energized over a circuit which may be traced H4, RAili, and the winding of RIM to battery. When energized over this circuit, the relay RIM operates to complete, at RAIN, an obvious holding circuit for itself and in so doing completes an obvious path for impressing ground potential upon the private conductor 'lc, thereby to mark the line H as busy. At RAi54, the relay RIM) completes an obvious circuitior energizing the slow-to-release relay RI40', causing the lastmentioned relay to operate and prepare, at RAI42, a circuit for energizing the relay Rl20. The operation of the relay Ri4fl also results in the venergization of the lower winding of the electro-polarized relay RIM in an obvious manner. The direction of current flow through the upper winding of this polarized relay is, how ever, such that the relay does not operate at this time. At RAISE, the relay Rliiil opens the above-traced path for impressing ground potential upon the distributor start conductor (H63. At RAi5i and RAI52, the relay RIBO opens two points in the above-traced operating circuit for the line relay RIM), thereby to clear the line ii of the shunt impedance represented by the exchange battery and the winding of RIM and to cause the release of RIBII. Upon restoring, the relay Rl60 opens, at RAISI, a point in the operating circuit for the cut-off relay RIM and opens at RAI62, a further point in the abovetraced path for impressing ground potential upon the start conductor Ci. Following the above-described operations, the connector switch, as shown in Figs, 2 and 3, is conditioned to respond to the impulses oi the first digit to be dialed at the calling substation A.

After removing the receiver li from its supporting hook, the calling party should deposit the coin representing the charge for local calls in the coin-receiving means provided at the substation A. Following this operation, the calling party may proceed to dial the digits of the directory'number designatingthe desired substation B. When a coin is deposited in the coin deposit channel of the coin-receiving means, the coin controlled mechanism operates to move the contact springs I09 into engagement, thereby to connect the windings of the polarized magnet I01 and the serially related discharge lamp I08 between the line conductor a and ground. At

this time the voltage of the exchange battery as impressed, between the line conductor a and ground through the windings of the two relays R230 and R225 is insumcient to cause current flow through the discharge device I08. Accordingly, the windings oi the electromagnetic de-' vice I01 are not energized at this time. During the dialing operation and each time the dial of the calling device I04 is moved of! normal, the shunt springs ii! of this device are moved into engagement to complete obvious paths for shortcircuiting the transmitter Hill and the receiver iOl. Also, during each return movement of the dial, the pulsing springs H8 are opened and closed a number of times depending upon the numerical value of the digit dialed. At the end of each return movement of the dial, the shunt springs lil are opened in the usual manner to interrupt the above-mentioned short-circuiting paths.

The line relay R230 responds to the impulses of the first digit dialed at the calling substation by completing the above-mentioned operating circuit for the vertical magnet 248 one or more times. Assuming, for example, that the directory number designating thedesired substation Bis I15, the line relay R230 restores and reoperates seven times during the impulses oi the first digit so that seven current pulses are transmitted to the vertical magnet 246. The circuit for energizing this vertical magnet may be traced as extending from ground at RA205 by way of RA23I, RA238, RA244 and the windelevated one step so that, at the end oi the first digit of seven impulses, these wipers are left standing opposite the seventh level" of bank contacts. As the indicated wipers are operated to the first vertical oil-normal position, the offnormal springs 24! are moved into engagement "to complete an obvious path for short-circuiting the upper winding of the relay R240. By virtue of the completion 0! the above-mentioned branch circuit including the lower winding of the relay R240 and the slow-to-release characteristic of this relay, it remains operated until shortly iollowing the end oi the first digit. Due to its slow-to-reiease characteristic, the hold relay R235 also remains operated during impulsing. At the end of the first digit and during the interdigit pause between the first and second digits, the line relay R230 remains operated for a sufllciently long time interval to cause the restoration of the relayR240. Upon restoring, the relay R240 opens, at RA243, a point in the circuit for energizing its lower winding and opens, at RA244, the above-traced impulsing circuit including the winding of the vertical magnet 246. At RM and RA242, the relay R240 removes the secondary winding of the transformer 241 from the loop circuit extending to the calling substation, thereby to terminate the dial tone signal being transmitted to the calling subscriber.

The impulses of the second restores at the beginning of each impulse of the second digit, a circuit is completed for energizing the rotary magnet 342 in series with the slowto-releaserelay R3iii, this series circuit extending from ground at RA205 by way of RA23i, RA238, RA244, C212, RA303, the winding of R3"), RA335 and the winding of the magnet 842 to battery. Each time the magnet 342 is energized over this circuit it steps the wipers 3M to 364, inclusive, one step in the rotary direction so that, at the conclusion of the second digit of seven impulses, these wipers areleft standing in engagement with the contacts terminating the conductors of the called line i2.

Upon operating, at the beginning of the first impulse of the second digit, the relay R3i0 completes, at RA8l3, a path in multiple with the armature RAMS, thereby to prevent the impulsing circuit extending through the winding of the rotary magnet 342 from being interrupted digit dialed at the calling substation are repeated through operaing the slow-to-release relay R320, causing the 75 current is reproduced by the receiver 10! so that.

through operation of the busy relay R300 as the wipers 3" to 334, inclusive. are moved over contacts terminating the conductors of busy lines.

.At RA3| I, the relay R3l0 opens a point in the last-mentioned relay to operate. Due to the slowto-release characteristics thereof, the relays R3l0 and R820 remain operated throughout the second and each succeeding series of impulses. Upon operating, the relay R320 opens, at RA323, a point in an alternative circuit, traced hereinafter, for energizing the busy relay R300. At RA32| and its associated resting contact, the relay R320 opens a point in the circuit, traced hereinafter, for energizing the lower winding of the line switching relay R330. At RA32I and RA322, the relay R320 completes the line test circuit including the winding of the busy relay R300, whereby this busy relay is energized each time the wipers 36l to,38l, inclusive, encounter a set of contacts terminating a busy line. At RA323, the relay R320 opens a point in the path, traced hereinafter, for impressing busy tone voltage upon the loop circuit extending to the calling substation.

Immediately the wipers 3Bl to 334,'inclusive, are moved into en agement with the contacts terminating the called line l2, this line is tested over the above-mentioned test circuit including the winding of the busy relay R300. Assuming the called line to be busy at the time it is thus selected. the busy relay is energized over this circuit which extends by way of the grounded private conductor of the called line, the wiper 303, RAMQ, RA32I. RA322. RA333 and the winding of R300 to battery. Upon operating, the relay R303 opens, at RA303, a point in the initially traced circu t for energizing the rotary magnet 302. At RAB. the relay R300 prepares a circuit. traced hereinafter, for energizing the ringing control relay R260. At RA303, the relay R303 prepares a oint in the above-mentioned circuit for energizine the release magnet 351. At RA300, the relay R330 prepares the above-mentioned path for impressing busy tone voltage noon the calling loop circuit. At RA30| the relay R300 prepares a circuit. traced hereinafter, for energizing the trunk hunting relay R325. At RA302, the relay R300 opens another point in the operating circuit for the line switching relay R330 and prepares a holding circuit for itself. Shortly following the end of the second digit the relays R3" and R320 sequentially restore in the order named and in an obvious manner. Upon restoring, the relay R320 completes the above-mentioned holding circuit for the busy relay R300 and thereafter opens the operating circuit for the busy relay. The holding circuit for the busy relay extends by way of the grounded release conductor C263, RA332, RA322 and its associated resting contact, RA333 and the winding of the relay R300 to battery. At RA324, the relay R320 completes the above-mentioned path for impressing busy tone voltage upon the calling loop circuit. This path may partially be traced as extending from the ungrounded terminal of the'busy tone source by way of-C333,

the condenser 338, RA33l, RA32l and RA303 to the lower side of the loop circuit extending to the calling substation. When this path is completed busy tone current is caused to flow over the calling loop circuit in the usual manner. This sweeper the calling party is informedthat the desired connection cannot be obtained. It is pointed out that following operation of the busy relay R300 the dialing of the third digit at the calling substation is without effect since with the relay R300 operated the pulsing circuit for the rotary magnet 342 is held open at the armatures RA303 and RA3I3 and the circuit for energizing the operating magnet 333 of the minor switch 350 is also interrupted at these two points. Hence, if the calling party continues the dialing operation and dials the third digit, the only response to the impulses of this digit is the alternate restoration and operation of the line relay R230. Following the operation of the busy relay R300, in the manner just explained, no further operation of the apparatus occurs until the connection is cleared 3 out at the calling substation. The manner in which the switch train is released when the calling subscriber replaces the receiver l0i upon its supporting hook H4 is explained in detail hereinafter.

Assuming the called line I2 to be idle at the time it is selected, battery'potential is present upon the private or control conductor thereof so that the busy relay R300 is not energized over the previously traced test circuit. Shortly following the selection of the line and during the interdigit pause between the second and third digits, the two relays R3l0 and R320. sequentially restore in the manner pointed out above. ,The relay R320, upon restoring, completes the abovementioned circuit for energizing the slow-to-opcrate line switching relay R330, this circuit extending by way of the grounded release conductor C263, RA302, the lower winding of R330, RA32I, RA332 and the wiper 353 to the negative battery terminal as connected to the private conductor of the called line i2 through the windings of the cut-oil relay conventionally embodied in the line circuit 3. When its lower winding is energized over this circuit, the relay R330 first completes, at the "2! contacts associated with RA334, a holding circuit for itself, this holding circuit extending by way of the grounded release conductor 021i, RA334 and the upper winding of R330 to battery. Thereafter the relay R330 opens, at RA333, a point in the above-traced test circuit including the winding of the busy relay R300, interrupts, at RA332, its own operating circuit as traced above, and completes, at RA332, a path for impressing ground potential upon the private conductor of the called line for the purpose of marking this line as busy in the bank contacts of the other connector switches having access thereto. 'This path extends by way of the grounded conductor 02', RA332 and the private wiper 363 to the private conductor of the called line. At RA33I, the relay R330'opens a point in the above-mentioned circuit forenergizing the trunk hunting relay R325 and prepares a circuit, traced hereinafter, for energizing the coin refund control relay R340. At RA335, the relay R330 prepares the above-mentioned circuit for energizing the operating magnet 353 of the minor switch 350 in accordance with the impulses of the third and final digit of the directory number designating the called substation B. At RA330, the relay R330 prepares a point in the circuit for energizing the ringing control relay R200. Finally, at RA33I, the relay R330 opens a point in the above-traced path for impressing busy tone voltage upon the calling loop circuit. Following operation of the relay R330, the operating magnet 356 is conditioned to respond to the impulses of third digit.

assays:

gized over this circuit at the beginning of the first impulse of the third digit, the relay R3l0 operates to complete the operating circuit for the relay R320, which latter relay, in turn, operates to open, at RA623, the above-mentioned alternative circuit for energizing the busy relay R300.

The two slow-to-release relays R3") and R320 remain operated throughout the iinpulses oi the Each time the operating magnet 366 is energized during the impulses of the third digit, it functions to advance the wipers 363 and 366 one step so that, at the conclusion of the third digit of live impulses, these wipers are left standing in engagement with their respective associated fifth contacts. When the indicated wipers are stepped to their respective first oifnormal positions, the oil-normal springs 368 are moved into engagement to prepare the alternative circuit for energizing the busy relay R300. This circuit is completed shortly following the end of the third digit and in response to the sequential restoration of the two slow-to-release relays R3l0 and R320. Specifically, this circuit extends from ground by way of the springs 358, RA323, and the winding of R300 to battery.v At RA306, the relay R300 prepares the above-mentioned circuit for energizing the release magnet 361. At RA306, the relay R300 prepares the circuit for energizing the ringing control relay R260. The last-mentioned circuit is completed shortly following the operation of the busy relay R300 and at the beginning of the next cycle of operation of the ringing interrupter switch forming a part of the ringing apparatus conventionally provided in the community exchange in common association with the various connector switches of the exchange. This circuit may be traced as extending from ground by way of the pickup conductor C328, RA336, RA304, C213, RA263 and the winding of R260 to battery. When energized over this circuit the relay R260 operates to complete a. holding circuit for itself, which holding circuit extends from ground at RA231 by way of RA294, RA262, RA263 and the winding of R260 to battery. Following the completion of this circuit the relay R260 opens, at RA263 and its associated resting contact, a point in its operating circuit as traced above. the relay R260 completes a circuit for projecting over the called line l2 coded ringing current of the particuar character corresponding to the called substation B, as selected by the minor switchstil. More particularly, the circuit traversed by the ringing current may, in the present case, be traced as extending from one terminal of the ringing current generator by way of contacts controlled by the above-mentioned interrupter switch, not shown, C310, the fifth contact of the set 362, the wiper 366, C266, RA26I, RA26I, RA20I, C261, RA346, the wiper 36!, one side of the line i2, the ringer and condenser bridged between the conductors of the line l2, the other side of the line i2, the wiper 366. RAMA. C116. RA206, RA266, RA256, C218, the wiper 353, the fifth contact of the set 35!, C216, the lower wind- At RAZBI and RA264,

ing of R266, RA266, RA261 and the exchange battery to the other side of the ringing current source. The resulting operation of the signal device provided at the called substation B serves to signal the subscriber at this substation that his substation is being called to the exclusion of other substations associated with the line i2. A portion of the ringing current is by-passed by way of the condensers 260 and 26l and the calling, loop circuit to energize the receiver provided at the calling substation, thereby to signal the calling party that the called substation is being rung. The desired conversational circuit between the calling and called substations is completed when the call is answered at the called substation B. 26

More particularly, when the receiver at the called substation is removed trom'its supporting, hook,- the hook switch embodied in this substation operates to connect a direct current bridge across the conductors of the line :2, thereby to complete 80 a circuit, substantially similar to that traced above and traversed by the ringing current, for energizing the lower winding of the slow-acting cut-oil relay R260. When energized by direct current traversing this circuit. the relay R260 25 stations and, in so doing, completes a loop circuit extending to the called substation. This loop circuit includes the windings oi the back-bridge relay R2|0 and may be traced as extending from ground at RA263 by way of the lower winding of R2i0, RA266, RA264. RA206, C216, RA368, the wiper366, one side of the called line l2, the direct current bridge connected between the conductors of the line l2, the other side of'the line l2, the wiper 36L RA366, C261, RA20I, RA26LRA26I and the upper winding of R2l0 to battery. Current for energizing the transmitter provided at the called substation is conducted to the transmitter over the circuit just traced. Current tor energizing the transmitter I00 provided at the calling substation is conducted to this transmitter through the windings oi the line and differential relays R230 and R226 and over the calling loop circuit. When energized over the loop circuit extending to the caled substation, the relay R2l0 operates to complete, at RA2I I. an obvious multiple path for impressing groundpotential upon the control conductor 200 of the trunkline 20. -At its armatures RA2i2 toRA2l6, inclusive, the relay R2l0 reverses the direction or current flow over the calling loop circuit in the usual manner.

The back-bridge relay R2i0, upon operating, also completes, at RA2i1, an obvious circuit for energizing the slow-to-operate relay R296 in parallel with the slow-to-release relay R230. The relay R290 now operates to complete a path for impressing booster battery potential upon the control conductor 20, this path extending from the positive terminal of the booster battery current source 266 by way of the resistor 236, 1=tA26l "and RA202 to the conductor 20. At RA293 and RA204, the relay R280 completes a similar path for impressing booster battery potential upon the release conductor 02'". After these paths are 6 completed the control conductor 20s and the conductor C2" are disconnected from ground at RA292 and RA! and their respective associated resting contacts. Shortly following the operation of R200, the relay R295 operates to complete, at RAIQI, an obvious holding circuit for itself. At RA286, the relay R295 opens the operating circuit for the relay R200. Zlf'he relay R280 restores its armatures RA29I, RA292, RA203 and RA! after an interval, thereby to disconnect the conductors 20s and C2" from the booster battery source and to reconnect these conductors to ground. Thus, it will be apparent that booster battery potential is impressed upon the conductors 2.0 and 02' for a short time interval immediately following the completion of the desired talking circuit between the calling and called,

substations. In the present case the application of positive booster potential to these conductors is without effect other than to increase the energization of the relays RIIO, R250, R260 and R330. On calls originating at regular substations of the system, however, and routed through the con-- 'm to prepare, at RAIlI, a path, traced hereinafter,

for impressing a positive or coin collecting potential of 110 volts upon the line conductor II- in order to cause the electromagnetic device I01 to operate and collect the coin deposited in the coin-receiving means provided at the calling substation. As explained previously, the relay RIIO is of the type such that when once operated it remains in its operated position so long as its lower winding is-energized regardless of the dig; reotion of current flow through its operating or upper winding.

The arrangement of the connector switch shown in Figs. 2 and 3' is such that the release of a switch train including this switch is entirely j under the control of the calling party. Thus,

following the completion of the connection between the calling substation A and the called substation. B, if the called party replaces his receiver upon its hook before the connection is m cleared out at the calling substation, the only resulting operation is the release of the backbridge relay R2I0 to reverse the direction of current flow over the calling loop circuit. When, however, the calling party replaces the receiver 1 III upon the switch-hook III, the calling loop circuit is interrupted at the springs III and H0, and the line relay R230 restores to interrupt the circuit for energizing the hold relay R235. The hold relay, upon restoring, completes, at RA238,

101 the above-mentioned circuits for energizing the release magnets 22'! and 351. The circuit for energizing the magnet-221 extends from ground at RA205 by way of RA20I, RA238, the ofl-normal springs 224 and the winding of the magnet 22! "1 to battery. When thus energized, the magnet 22'! operates to cause the restoration of the wip ers "I to 804, inclusive, to rotary and vertical normal in the usual manner. If the back-bridge relay R2I0 is operated at the time the release magnet 22'! is energized, the loop circuit extending to the called substation is interrupted during the release of the switching mechanism, thus causing the restoration of the back-bridge relay. Upon restoring, the relay R2I0 opens, at RAZIl, a point in the operating circuit for the relays R290 and R2". When the enumerated switch wipers are returned to their respective normal positions, the oil-normal springs 220 are opened to deenergize the magnet 221. The circuit for energizing the release magnet 35'! extends from ground at RA20I by way of RA23I, RA2I0, C214.

RA305 and the winding of the magnet 351 to battery. When this circuit is completed, the magnet 351 operatesto cause the wipers 250 and 354 of the minor switch 250 to be returned to their .mespe'ctive home positions, at which time the of!- normal springs 350 are opened to interrupt the above-traced alternative circuit for energizing the busy relay R300, causing this relay to restore and ppen, at RAIII, the operating circuit for the release magnet Ill.

When the hold relay R235 restores, in the relay R295, causing the last-named relay to restore. Following the restoration of the indicated relays and switching apparatus, the connector switch is fully released. V

When the two relays R2I0 and R235 restore during the release of the connector switch, ground potential is removed from the private conductor 20c of the trunk line 20, thereby to deenergize the relay RI50. 'When ground potential is removed from the private conductor 20 of the trunk line 20, the finder switch I4 is released in the usual manner and the'finder-connector link illustrated is marked as idle in the bank contacts of the distributor I 5. Upon restoring, the relay RI50, at

RAIN, opens the operating circuit for the relay RI ,and completes a circuit extending by way of RAI42 for energizing the relay RI20. At RAI53, the relay RI50 opens the path for impressing ground potential upon the private conductor c and a point in its own holding circuit. The relay RI20, upon operating, completes, at RAI23, an obvious multiple holding circuit for the relay RI30. At RAI2I and RAI22, the relay RI20 completes the above-mentioned paths for impressing apositive or coin collect potential of 110 volts upon the line conductors I I. and I I b of the calling line II.; More particularly, the 110 volt source is connected across the discharge device I08 over a circuit which extends from the ungrounded terminal ofthesource bywayofCIfl,RAI3I,RAI2I, the conductor a, the springs I09, the windings of the magnet I01 and through the discharge device I00 to the grounded terminal of the source. The magnitude of this voltage is such that the gas contained in the discharge device I08 is ionized to permit the flow of current therethrough, so that the windings of the magnet I01 are energized.

. The polarity of the current traversing the abovetraced circuit following ionization of the device I08 is s ch that the armature associated with the magnet I0! is pivoted in a direction to cause the coin deposited in the coin deposit channel of the coin-receiving means to be directed into the coin collect channel in the usual manner. Operation of the armature associated with the magnet It! also results in disengagement of the contact springs M9 to interrupt the series circuit including the windings of the magnet I01 and the discharge device I08. Thus, the deposited coin is collected during the release of the operated switch train and after the conversation held over the established connection is terminated. Shortly following the energization of the magnet I01 the slow-to-release relay Ritd restores to open, at RAi s I, one of the multiple holding circuits for the relay Rltfi. At RAIM, the relay Rldt opens the operating circuit for the relay RI20, causing the last-mentioned relay to restore. When the relay RI20 restores it interrupts the remaining holding circuit for the electropolarized relay RIM, causing the latter relay to restore. At its armatures RAI 2i and RAI22, the relay RI20, upon restoring, also opens the above-traced path for impressing the positive coin collect potential upon the conductors l I a and I is of the line H.

In the event the called line I2 is busy at the time it is selected by the connector switch illus-. trated in Figs. 2 and 3, the back-bridge relay R2I0 embodied in this switch doesnot operate. Accordingly, the two booster battery control relays R290 and R295 are not caused to operate. Also, the direction of current flow over the calling loop circuit is not reversed and the polarized relay RI30 of the apparatus I7 remains in its restored position. When the usual busy tone signal is transmitted to the calling substation, the calling party is expected to abandon the call by replacing the receiver i 0| upon its supporting hook I It. In response to this operation. the calling loop circuit is interrupted and the relays R280, R285 and R300, which are the only operated relays in the connector switch, are caused sequentially to restore in an obvious manner. The hold relay R235, upon restoring, functions to remove ground potential from the control conductor 20c and to complate, at RA28B, the previously traced operating circuits for the release magnets 22? and 357, thus causing the minor switch 350 and the switching mechanism of the connector switch to be restored to normal in the manner previously explained. When ground potential is removed from the con trol conductor ills of the trunk line 20, the finder switch It is released and the relay RI 50 is deenergized and restores to complete the previously traced circuit for energizing the relay RI20. Upon operating, the relay RI20 completes, at RAi2I and RAI22, paths for impressing the negative potential of the 110 volt coin refund current source upon both conductors of the calling line i I. More particularly, the voltage of this source is impressed across the electrodes of the discharge tube I00 over a circuit extending from the negative terminal of the coin refund current source by way of CI33, RAIliI, RAI2I, the conductor a, the springs its, the windings of the magnet I01 and through the device I08 to the positive terminal of the coin refund current source. The magnitude of this voltage is such that the discharge device I08 is rendered conductive, so that the windings of the magnet I01 are energized by current traversing the circuit just traced. The direction of current flow over this circuit is such windings of the magnet I01 is broken.

that the magnetlfl pivots its associated armature in a direction to cause the coin deposited in the coin deposit chute of the coin-receiving means to be directed into the coin refund channel of this means. Operation of thearmature controlled by the magnet I01 also results in disengagement of the contact springs I09. whereby the circuit serially including the discharge device I00 and the Shortly thereafter the relays RIM and RI20 are caused to restore in the order named and in the manner previously explained, the last-mentioned thereof functioning to open the holding circuit for the relay RISE causing the latter relay to release. Thus, the operated switch train is fully released and the coin deposited by the calling party, incident to initiation of the call, is refunded.

Referring now to the operation of the apparatus to extend a connection to the operator's position I 9 in the central omce, if it be assumed, for example, that the above-described call initiated at the substation A is a trunk call and further that the finder switch It and the connector switch shown in Figs. 2 and 3 are utilized in completing the desired connection, the calling party, after removing the receiver IOI from its digit. the wipers SSI to 38$, inclusive, of the connector switch are elevated to a position opposite the level of bank contacts terminating the link lines extending to the repeaters associated with the trunk lines extending to the central ofllce, all in the exact manner previously described with referenceto the call routed to the substation B. In this connection, it is pointed out that the uppermost. level or levels of bank contacts embodied in the connector switch are utilized to terminate the indicated link lines. During the vertical movement of the wipers and when the wipers are moved to a position opposite the first of the contact levels terminating link lines extending to the two-way repeaters,

the oil-normal springs 209 are moved into engagement to prepare a circuit, traced hereinafter, ior energizing the slow-to-release switching- .through relay R200. When a second digit of one impulse is dialed at the calling substation, the rotary magnet 86! is energized and operates to rotate the wipers SBI to 36$, inclusive, into engagement with the first set of contacts in the selected contact level. Assuming that the link line It extending to the repeater I 0 is terminated at the third set of contacts in the selected level and further that the trunk line I0 is the first available idle trunk line extending to the central oflice, the three relays R300, R320 and R325 cooperate with the rotary magnet M2 to cause the wipers to be rotated until they encounter the third set of contacts in the selected level. Thus, the private conductors of the link lines extending to the repeaters associated with the respective first and second interofiicetrunk lines both have ground potential thereon by virtue of the busy condition of the associated repeaters. Accordingly, when the wiper 063 encounters the grounded contact of the first contact set during the first step taken by the wipers 36I to 36$, inclusive, the previously traced circuit is completed for energizing the busy relay R300, it being pointed out that the two slow-acting relays R3" and R320 are operated at this time. when the relay R3i0 restores shortly following the operation of the busy relay R300, it completes the previously 5 mentioned circuit for energizing the trunk hunt-l ing relay R325, this circuit extending by way of the grounded private conductor of the first link line, the strap 310 between the private and extra control contacts of the first contact set in the selected level, the wiper" 382, RA33I, RA30I, RA3II, the armature 343 and the winding of R325 to battery. When this circuit is completed, the relay R325 operates to complete, at RA328, a holding circuit for itself, which holding circuit extends from ground at RA230 by way of C209, RA320, the armature 343 and the winding of R325 to battery. At RA321, the relay R325 completes a circuit for energizing the relay R320 and 1 P the rotary magnet 342 in parallel, one branch of go this circuit extending by way of thegrounded release conductor C21i, RA32'I, RA3|2 and the winding of R320 to battery, and the other branch extending by way of C211, RA32'I, RA335, and the winding of the magnet ,342 to battery. By

5 virtue of the completion of this circuit, the'slowto-release relay R320 is maintained in its operated position. The rotary magnet 342, when energized over the above-traced circuit, operates to step the wipers to 334, inclusive, into engagement with the second set of contacts of the selected contact level and to open, at the armaure 343, the holding circuit for the relay R325. The relay R325 now restores to open, at RA325, a further point in its holding circuit and to interrupt, at RA321, the above-traced circuit for energizing the relay R320 and the magnet 342 in parallel. As a result, the magnet 342 restores its armature 343 to recompiete the previously traced test circuit including the winding of the relay R325. Since, in the assumed case, the link line terminated at the second set of contacts of the selected contact level is also associated with a busydnteroflice trunk line, ground potential is present upon the private and extra control contacts of the second contact set and the trunk hunting relay R325 is again energized over the test circuit as traced above. Accordingly, this relay reoperates to recomplete, at RA325, its holding circuit and to recomplete, at RA321, the circuit for energizing the relay R320 in parallel with the rotary magnet 342. As a result, the wipers 30I to 364, inclusive, are operated into engagement with the third set of contacts of the selected level, which contacts are assumed to ter- 55 minate the conductors of the link line i3 associated with the idle interofllce trunk line l0. It will be understood, in view of the foregoing explanation, that in any case the interrelated operation of the relay R325 and the rotary magnet 342 continues until the wipers i to 304, inclusive, are advanced into engagement with a set I of contacts terminating an idle one of the link lines or until all of the link lines have been tested. Since, in the present case, the third link line 65 i3 is assumed to be idle, negative battery potential as derived through the winding of the relay R510 is present upon the control or private conductor I30 so that the trunk hunting relay R325 is not energized over the previously traced test circuit when the wipers 35i to 364, inclusive,

7 mediately the wiper 363 is moved into engagetheconductors 20c and C2".

ment with the contact terminating the private conductor I36 having negative battery potential thereon, the busy/relay R300 restores to prepare the previously traced circuit for energizing the lower winding of the line switchingrrelay R330. 5 Shortly thereafter the relay R320 restores to complete the last-mentioned circuit. The relay R330 now operates to complete, at RA334, its holding" circuit, as traced above, and to open, at RA333, a further point in the circuit for energizing the busy relay R300. At RA33I, the relay R330 prepares the circuit for energizing the relay R340. At RA332, the relay R330 opens a point in its operating circuit and completes a path for impressing ground potential upon the private or control conductor i3e,'this path extending by way of the grounded conductor 621i, RA332 and the wiper 303 to the conductor i3e. At RA334, the relay R330 also completes a circuit for ener-' gizing the switching-through relay R200, this circuit'extending from ground at RA231 by way of RA294, C21i, RA334, C210, the oil-normal springs 209, the secondary winding of the transformer 215 and the winding of R200 to battery. Upon operating, the relay R200 completes, at

RA204, a multiple path including the primary winding of the transformer 2| 0 for impressing ground potential upon the private conductor 20s of the trunk line 20, thereby to maintain the finder s'witch i4 operated and the relay Ri50 energized. At-RA200', the relay R200 completes the circuit for energizing the relays R230 and R285, thereby to cause the sequential operation of these two relays followed by the restoration of the relay R200, in the manner previously explained. During the interval when the relay R230 is operated positive booster battery potential is substituted for ground potential upon each of The relay R235, upon operating completes a holding circuit for itself, this holding circuit extending from ground by way of the left winding of the transformer 2i8, RA204, RA291 and the winding of R295 to battery.

At RA20I and RA206 and their respective associated armatures RA202 and RA201, the relay R200, upon operating, connects the trunk line conductors 20. and 20b to the link line conductors C261 and C215, thereby to switch the calling loop circuit through to the repeater i0. At RA202 and RA201 and their respective associated contacts R0203 and R0200, the relay R200 opens two points in the loop circuit as initially estab lished and including the windings of the relays R225 and R230, thereby to cause the sequential restoration of the relays R230 and R235. Before the hold relay R235 restores to remove ground potential from the respective release conductors C289 and 02", however, multiple ground potential is impressed upon the conductor C2" in the repeater l3 for the purpose of maintaining the relays R200, R235 and R330 operated. Thus, when ground potential is impressed upon the private conductor I ie'of the link line l3, this line is marked as busy in the bank contacts of the other connector switches having access thereto: and a circuit is completed for energizing the slow-acting relay R510. This circuit extends by way of the grounded conductor I38, RA502 and the winding of R510 to battery. Upon operating, the relay R510, at RA51I and RA512, extends the calling loop circuit through the windings of the repeating coil 520 and the windings of the line relay R400 so that the last-mentioned relay is energized thereover. Upon operating, the relay 75 operates, it completes, at RA422, two multiple paths for impressing ground potential upon the private conductor I30; one of these paths extending from ground at RA453, the other pathextending from ground through the winding 466 and both thereof. extending by way of RA422v to the private or control conductor 13. The completion of these paths prevents the release of the operated relays R330, R295 and R205 in the manner indicated above. The relay R420, upon operating, opens, at RA42I, a point in the circuit, traced hereinafter, for energizing the relay R560. At this same armature, the relay R420 prepares a circuit for energizing the pendulum'-type relay R450. At RA423, the relay R420 prepares a circuit for energizing the ring cut-off relay R430 and, in so doing, completes a circuit for transmitting ringing current over both sides of the trunk line l to energize the signal device 502 provided at the operator's position IS. The circuit traversed by the ringing current extends from' one terminal of the ringing current source by line conductors I and I0 of the line l0, the

condenser 503, the winding of the signal device 502, the contact springs 506, and the exchange battery to the other terminal of the ringing current source. The resulting operation of the signal device 502 indicates to the operator that an incoming call on the line l0 should be answered. At RA424, the relay R420 completes a circuit for transmitting the usual ring-back tone signal current to the calling substation. More particularly, the high potential terminal of the ringing current source is connected to one side of the calling loop circuit over a path including the conductor C438, the condenser 431, RA436,, RA424 and C584. When this path is completed, ringing current is caused to traverse the calling loop circuit to energize the receiver provided at the calling substation A, whereby the calling party is informed that the operator is being signaled. Following the operations just described no further operation of the apparatus occurs until the operator answers the call.

To answer the call the operator attending the position I9 inserts the plug terminating her telephone set in the call and answer jack 50l, thus completing the desired conversational circuit between the calling substation A and the operator's telephone set. When this operation is performed, the contact springs 506 are disengaged to open the above-traced circuit for energizing the signal device 502. Simultaneously the springs 501 are moved into engagement to complete the circuit for energizing the relay R430, this circuit extending from ground by way of the switch springs 509 and 508, the springs 501, the pulsing springs of the calling device 504, the simplex loop including both sides of the line l0, C583, RA423, RA434, the upper winding of R430 and RA433 to battery. When energized over this circuit, the relay R430 closes the X contacts associated with RA43I to complete an obvious holding circuit for itself. Thereafter the relay R430 fully operates to complate a circuitfor energizing its two windings in series, this circuit extending from ground at over the line l0 to the operator's position l9 and back over the calling loop circuit to the calling substation A, thus terminating the ring-back tone signal. At RA434, the relay- R430 completes the 3 previously mentioned circuitffor energizing the -two relays R530 and R540 in series, this circuit .extending. by way-of the-grounded conductor C583, RA423, RA434, the resistor 404, RAM,

-RA402, C58l, the winding of R540 and the two windings of R530 to battery. Due to the relatively high resistanceof the. series connected windings of R530; the -relay R540 does not operate whenthis circuit is completed. The relay R530, however, operates to complete-at RA53I, the circuit for energizing the pendulum-type relay R450, this circuit extending-from ground by way of RA53I, C511, RA42| and the windingnof R450 to battery. When energized over this circuit, the relay R450 attracts its associated armature RA455 to initiate vibration of the weighted armature 456. At RA454, the relay R450 completes an obvious holding circuit for-the relay R420. At RA453, the relay R450 opens one of the previously traced multiple paths for impressing ground potential upon the private conductor '30 and, in so doing, removes the short circuit from the transformer winding 466 so that paystation tone current is caused to traverse this winding. More particularly, paystation tone voltage is impressed, through the condenser 22, upon the control conductor I I a of the calling line I I by the alternating current source 2|. This voltage is impressed,

through the finder switch I4, between the private C585 of the repeater l8 over a path including the condenser '468 and the two armatures RA451 and RA442. As a result, paystation tone current is caused to traversethe windings of the repeater 520 so that the usual paystation tone signal is transmitted by way ofthe trunk line l0 and the repeater 500 to the receiver of the operator's telephone set; Through reproduction of this voltage, the operator is informed that the calling substation is of the paystation type. A predetermined time interval following energization of the relay R450, the vibrating armature 456 settles into resting engagement with its associated armature RA455 to hold completed an obvious circuit for energizing the slow-to-operate relay R440. The relay R440 operates after an interval to complete, at RA44I, an obvious path for'shortcircuiting': the winding 466 of the transformer 465, thereby to terminate the paystation tone signal impressed upon the line conductors C513 and and to complete a multiple path for maintaining ground potential upon the control conductor Ila At RA442, the relay R440 disconnects the secondary winding 451 of the transformer 455 from the line conductor C505.

The relay R450, upon operating, also functions to reverse, at its armatures RA45I, RA452, RA458 and RA455, the direction of current flow over the calling loop circuit in an obvious manner. As a result of this current reversal, the relay RI30 included in the trunk circuit apparatus I1 is caused to operate to prepare, at RAIII, the previously traced paths for impressing the positive potential of the 1l0'volt coin collect current source upon the line conductors II. and b of the calling line II.

If the operator desires to recall the paystation tone signal she may do so by momentarily withdrawing from the jack 50I the plug terminating her telephone set. When the call and answer plug is withdrawn from the jack 50!, the springs 501 are disengaged to interrupt the previously traced circuit for energizing the two relays R530 and R540 in series. Accordingly, the relay R530 restores togopen, at RA53I, the previously traced operating circuit for the relay R450. The last-named relay, in turn, restores to open, at RA455 and its associated weighted armature 455, the operating circuit for the relay R440, causing the last-named relay to restore. Upon restoring, the relay R450 also reverses, at its armatures RA45I, RA452, RA450 and RA459, the direction of current flow over the calling loop circuit. Since the relay Ri30of the trunk circuit I1 is now operated, the last-mentioned reversal of the direction of current flow over the calling loop circuit is without eifect. When the operator reinserts the plug terminating h'er cord circuit in the jack 50I, the previously traced operating circuit for the relay R530 is recompleted, causing this relay and the relay R450 sequentially to operate in the order named. As a result, paystation tone current isagain caused to traverse the winding 455 of the transformer 455 and the secondary winding 451 is again connected between the line conductors C513 and C585. After a predetermined time interval required for vibration of the weighted armature 455 to cease, the slow-to-operate relay R040 operates to terminate the signal in the manner explained above.

After the connection between the operators position I and the calling substation A is established in the manner just explained, the operator, upon ascertaining the party or substation desired by the calling party, mayinstruct the calling party to make the appropriate coin deposits. It may occur that an improper coin deposit is made by the calling party, in which case the operator may desire to refund all of the deposited coins and request a second deposit of the coins representing the assessed charge. A refunding operation of this character may be performed under the control of the operator at any time. To this end, the operator momentarily operates the key 505 to its oilnormal position. In response to this operation, the contact springs 500 and I0 are closed and the springs 505 and 509 are disengaged. As a result, the booster battery current source 5| I and the resistor 5I2 are serially included in the previously traced circuit for energizing the windings of the two relays R530 and R540 in series.

The increased current flow over this circuit causes operation of the relay R540. Upon opcrating, the relay R540 completes, at RA54I, the previously mentioned circuit for energizing the relay R450,this circuit extending from ground by way of RA54I, C515, RIM and the winding of R450 to battery. Upon operating, the relay R450 completes, at RA452, a local loop circuit including the resistor 454 for maintaining the line relay R400 operated. At RA46I and RA453, the relay R450 opens two points in the calling loop circuit. At these same armatures and their respective associated working contacts, the relay R450 impresses the negative 110 volt potential 01 the coin refund current source upon bothsides of the calling loop circuit. As a result, the discharge device I05 is rendered conductive and current flows through the windingsof the magnet I01 over a circuit extending from the positive terminal of the 110 volt source by way of the discharge device III, the windings of the magnet I01, the contact springs I00, the conductor II, RAI2I, the conductor 20., RA202, RA20I, C251, RA345, the wiper "I, the conductor I3, RA45I and CI33 to the negative terminal of the 110 volt source. The direction of current flow over this circuit is such that the armature controlled by the polarized magnet I01 is pivoted in a direction to cause the deposited coin or coins to be refunded to the calling party through the coin refund chute of the coin-receiving means. When the key 505 is released and allowed to restore to its normal position, the springs 508 and 5| 0 are disengaged and the springs 508 and 509 are moved into engagement. Accordingly, the booster battery source 5 is excluded from the series circuit including the windings of the relays R530 and R540, causing the last-mentioned relay to restore. Upon restoring, the relay R540 opens the previously traced operating circuit for the relay R450. The relay R450,.in turn, restores to disconnect the line conductors I3. and I3b from the negative terminal of the coin refund current source and to extend the calling loop circuit to the line terminals of the line relay R400. At RA452, the relay R450 also interrupts the local loop circuit including the windings of the line relay R400.

After the correct coin deposits have been made by the calling party, the operator attending the position I0 may extend the connection to the desired substation and complete the desired conversational circuit between the calling and called substations in the manner conventionally employed in manual offlce practice. During the release of the connection and when the operator withdraws the plug terminating ;her cord circuit from the jack 50I, the contact springs 501 are disengaged to open the series circuit including the windings of the relays R530 and R540. Thus,

the relays R530, R450 and R440 are 'zeaused sequentially to restore in the manner previously explained. When the callingsubscriber thereafter replaces the receiver IOI upon the supporting hook I I4 to interrupt the calling loop circuit, the relays R400, R4I0, R420, R430 and R510 are caused sequentially to restore in an obvious manner and in the order named. The restored to rotary and vertical normal-in the assenar RA42I, C510 and the upper winding of R500 to usual manner. When these wipers are returned to their respective home positions, the operating circuit for the release magnet is opened at the off-normal springs 224. In addition, the of!- normal springs 205 are disengaged to open a further point in the operating circuit for the relay R205. At RA204, the relay R205. p n restoring.-, disconnects ground potential from the private conductor 20s of the trunk line 25, thus causing the release of the finder switch i4 and the restoration of the relay RI 50 followed by the operation of the relay- R l25. when the relay Ri2l operates, it connects. the line conductors ii. and ii of the calling line to the positive terminal of the 110 volt coin collect current source so that themagnet I01 is energized by current of the proper polarity to cause the armature associated with this magnet tooperate in the manner required to pass the deposited coins into the coin collect chute of the coin-receiving means. Shortly following the operation of the relay Ri20, the relay Ri40 restores to cause the sequential restoration of the relays Rl20 and Rll in the manner previously-explained. Thus, the connection is fully released and the apparatus involved therein is conditioned for further use.

In the event the connection is released at the calling substation before it is cleared out at the operator's position la, the relays R405, R4l0, R420, R400, R510, R450 and R440 are all caused to release in an obvious manner. when these relays are restored to normal, ground potential is removed from the private conductor II of the link line it so that the connector switch shown in Figs. 2 and 3 is released in the manner pointed out above. Also, the trunk circuit apparatus ll operates to cause the coin collecting operation to be performed, after which it releases to initiate the release of the finder switch l4. During the release of the indicated relay equipment embodied in the repeater l5 and when the relay R420 restores, an alternative circuit, traced hereinafter, is completed for energizing the relay R580, whereby this relay, the relay'R550, the relay R510 and the relay R550 are caused to re operate toextend a connection to an idle one of the connector switches provided in the community exchange, all in the manner pointed out immediately hereinafter.

To initiate, at the operator's position is, a call intended for one of the substations associated with a line terminating at the distant community exchange, the operator inserts the plug terminating her cord circuit in the Jack "I and dials the directory number of the desired substation. If, for example, the substation A is being called from the operator's position I0, the operator dials the directory number designating this station. When the operator inserts the call and answer plug in the jack 5!, the previously mentioned circuit is completed for energizing the relay R530, this circuit extending from ground by way of the springs 500 and 508, the Jack springs 501, the pulsing springs of the call.- ing device 504, the simplex loop including the conductors l0 and ills of the line i0, C583, RA428, the resistor 404, RA403, C582, RA552 and the lower winding of R530 to battery. The relay R530, uponoperatins, prepares, at RA532, a loop circuit to the line circuit i5 associated with the link line l3. At RA55I, the relay R530 completes a circuit for energizing the upper winding of the relay R580, this circuit extending from ground at RA53I by way of C511,

battery. The relay R550, upon operating, complates, at RA552,, a circuit for energizing'the slow-acting relay R5l0,,this circuit extending from ground at RA52i by way of C5", RA42I, C510, RA5I2 and the winding of R515 to battery. At RA552, the relay 'Rltl prepares a-cir-' cult, traced hereinafter, for energizing the relay Rlll. At RAIII and RA554, the relay R550 prepares two additional points in the above-mentioned loop circuit extending by way of the line it to-the line circuit l5. This loop circuit is completed in response to operation 'of the relay R510 and may partially be traced as extending by way of the line conductor its, RA45I, RA45i, C512, M5", the. upper. right winding of the transformer 520, RAIN, RA522, the upper winding of R550,RA554, the lower right winding of the transformer 520, M512, 0555, RA45I and RA402 to the opposite line conductor its. Due to the relatively low resistance of the upper winding of the relay R550, this relay does not operate at this time. when the above-traced loop circuit is completed, the line relay in the -line circuit it operates to impresse ground potential upon the distributor start conductor Cl" and to mark the line It in the bank contacts of the finder switches. Assuming, for example, that'the finder-connector link illustrated is the link assigned to the use of the calling line it.

when ground potential is impressed upon the conductor Cl 62, the finder switch i4 is started in operation to search for the marked line it. When the calling line is found the finder switch i 4 operates in the usual manner to switch the above-mentioned loop circuit through to the connector switch of Figs. 2and 3, causing the relays R220, R225 and R240 sequentially to operate in the order named and in the manner explained previously with reference to the call initiated at the substation A. relay R225 operates, it functions to impress ground potential upon the private conductor of the link line 20, which groundpotential is applied through the finder switch 14 and the line circuit It to theprivate conductor lie of the When the hold conductor is grounded, the relay R550 is enersized-over a circuit including this conductor, RA562 and the lower winding of R500. Thus, a holding circuit is established for the relay R580. When ground potential is impressed upon the conductor its the lower winding of the relay R550 is energized over an obvious circuit. Since the currents respectively traversing the upper and lower windings of R550 are at this time in opposition the relay R550 does not operate when its lower winding is energized.

The connector switch illustrated in Figs. 2 and 3 responds to the three digits of the directory number designating the substation A by operating to select the line H, to test the idleor busy condition of this line, to return busy tone to the calling operator in the event the line is busy, and

to project ringing current of the proper code over calling device 504, the above-traced circuit forenergizing the relay R530 is interrupted a number of times depending upon the particular digit dialed. Thus, the relay R530 follows the dialed impulses and, through operation of RA522, re-

peats the impulses to the connector switch shown in Figs. 2 and 3. When the wipers "I to 354,

inclusive, of the connector switch are moved into engagement with the contacts terminating the conductors of the called line H, a circuit includ- 5 ing the resistor 315 is prepared for energizing the relay R340. Assuming the line H to be idle at the time it is selected, this circuit is completed in response to operation of the line switching relay R330 and may be traced as extending from ground by way of the resistor 515, the wiper 582,

RA33| and through the winding of R340 to battery. The relay R340, upon operating, prepares a circuit for energizing the slow-to-release relay Upon operating, the line switching relay also completes, at RA334 and RA332, a path extending by way of the private wiper 353 for impressing ground potential upon the private conductor I '0 of the called line H, thereby to mark the line II as busy and to energize the cut-oflf relay RI".

The relay Rl50, upon operating, disconnects the winding of the line relay R150 from the line ii and completes the operating circuit for the relay RI40. The relay Ri40, in turn, completes the circuit for energizing the polarizing winding of the relay RI 30 and prepares the operating circuit for the relay R120.

When the call is answered at the called substation A, the desired conversational circuit extending from the operator's telephone set to the called substation is completed in the manner previously explained. At this time the back-bridge relay R2l0 is caused to operate, in the manner previously explained, to cause the operation of the booster battery control relays R290 and R205 and a reversal of the direction of current flow over the loop circuit extending to the repeater l8. The resulting operation of the indicated booster battery control relays is without .eflect. 40 Reversal of the current flow over the loop extending to the repeater l8 causes the two windings of the relay R550 to be cumulatively energized.

Accordingly, the relay R550 operates to complete, at RA55I and RA552, the previously traced 45 circuit for energizing the relays R530 and R540 in series. Following the completion of this circuit the relay R550 opens, at RA552 and its associated resting contact, the initially completed operating circuit for the relay R530. If desired, the

50 arrangement just described, wherein the backbridge relay R550 and the line relay R400 are arranged to control the resistance of the simplex circuit including the two sides of the line l0, may be utilized to control a supervisory signal control 55 relay of the marginal type provided at the operator's position IQ for purposes of call supervision. An arrangement of this character is disclosed in the copending application of John H. Voss, Serial No. 215,786, filed June 25, 1938.

60 When the call is answered at the called substation A, a loop circuit is completed between this substation and the connector switch shown in Figs. 2 and 3, this loop circuit serially including the operating winding of the relay Ri30. The

65 direction of current flow over this loop circuit is such that the polarized relay Ri30 operates to prepare, at RAl3l, the previously traced paths for impressing the positive potential of the coin collect current source upon the conductors II. and

70 its of the line I I.

Following the completion of the talking circuitin the manner Just explained, the operator may desire to make coin refunds to the called party.

For example, if the call routed from the oper- 75 ators position to the substation A is a delayed call and the party at the substation A desires to pay for the call, a coin refund operation may be required incident to the use of the connection. To this end, the operator momentarily operates the key 505 to cause the operation of the relay R540 in the manner previously described. Upon operating, the relay R540 completes. at RA54I, a path including the conductors C515 and C514 for impressing ground potential upon both sides of the loop extending by way of the line i3 and the line switch l5 to the connector switch shown in Figs. 2 and 3. As a result, the differentially wound relay R225 is unbalanced and operates. The relay R225, upon operating, completes the previously mentioned circuit for energizing the relay R345, this circuit extending from ground at RA225 by way of C255, RA34I and the winding of R545 to battery. When the key 505 is restored to normal the relays R540 and R225 sequentially restore to interrupt the circuit Just traced. Upon operating, the slow-to-release relay R345 opens, at RAI45 and RAB, two points in the established talking circuit extending to the called substation. At these same armatures and their respective associated working contacts, the relay R345 completes paths for connecting the negative terminal of the 110 volt coin refund current source to each side of the called line H, one of these paths extending by way of Cl33, RA346 and the wiper "I to the line conductor lit and the other path extending by way of RA348 and the wiper 254 to the conductor HI. When the negative coin refund potential is impressed upon the conductor III, the magnet I01 is caused to operate, in the manner previously explained, to refund the deposited coin or coins to the called party. Shortly following the restoration of the relay R225 in response to release of the key 505, the relay R345 restores to open the two paths Just traced and to recomplete the talking circuit between the called substation and the operator's position l0.

As indicated previously, coins deposited in the coin-receiving means provided at the called substation A are automatically collected during the release of the operated switch train. The release of the switch train is entirely under the control of the operator attending the position 19. More particularly, when the connection is cleared out at the operators position it, the relays R530 and R230 sequentially restore. Shortly following the release of the relay R230, the hold relay R235 restores to remove, at RA236 and RA231, ground potential from the private conductors 20 and lie. The relay R230, upon restoring, completes the previously traced circuits for energizing the release magnets 221 and 351, thus causing the wipers 36l to 364, inclusive, to be restored to rotary and vertical normal and the minor switch 550 to be released. From this point on, the release of the connector switch shown in Figs. 2 and 3 and of the line switch i6 is accomplished in the exact manner described previously. When ground potential is removed from the private conductor lie of the link line I3,

'the relays R550 and R560 are deenergized and restored. The relay R510 is deenergi'zed and restores'shortly following the restoration of the line relay R530 to open the operating circuit for R510 as traced above. Thus, the repeater I8 is fully released and all of the apparatus utilized in setting up the connection is conditioned for further use.

During the release of the connector switch and when ground potential is removed from the private conductor a of the called line II, the cutoff relay RIW restores to interrupt the operating circuit for the relay RIIII and to complete the operating circuit for the relay RI20. The resulting operation of the relay RI20 causes the magnet I01 to operate in a manner such that the coins on deposit in the coin-receiving means at the substation A are collected, all in the manner previously explained. The relay RI40, upon restoring, causes the sequential restoration of the relays RI20 and'RI30 in the exact manner described above.

From .the foregoing explanation, it will be apparent that on local calls originating at one of the paystations served by the automatic switch- .ing equipment of the community exchange, the

coin refunding and coin collecting operations are performed under the control of paystation control circuit apparatus, such, for example, as the apparatus I'I, after the calls are terminated and during the release of the switch trains through which the calls are routed. n trunk calls routed from the paystations to the operators position I8, on the other hand, coin refunding operations may be performed at any time after a connection to the operator's position is established under the control of the operator and through operation of the apparatus provided in the repeater associated with the interoflice trunk line in use. On such trunk calls, however, coin collect operations are only performed after the connection in use is cleared out and during the release of the operated switch train, the coin collecting operations being controlled by paystation, control circuit apparatus, such, for example, as the apparatus I I, associated with the paystation line in use. Finally, on delayed calls originating at the operator's position I9 and routed to substations of the paystation type served by the automatic switching apparatus located at the community exchange, coin refunding operations may be performed under the control of the operator at any time after a connection is set up between the operator's position and the called substation, these coin refunding and coin collecting operations being obtained through appropriate manipulation of the key 505 and the resulting operation of the control apparatus provided in the repeater and the connector switch in use. Here again, the paystation control circuit apparatus associated with the called paystation line is utilized to control the coin collecting operations. I

Referring now more particularly to Fig. 6 of the drawings, the paystation control circuit apparatus there illustrated is arranged for booster battery control and may be substituted in the system of Figs. 1 to 5, inclusive, for the relays RI20, RI30 and RIM! of the apparatus II. In brief, the apparatus shown in Fig. 6 comprises a line switching relay R800, a coin collect control relay R8I0 of the marginal type, and a pair of control relays R620 and R830 arranged to control the energization of the line switching relay R600. In order to substitute this apparatus for the apparatus II in the system shown in Figs. 1 to 5, inclusive, the terminals I8I, I02, I83, I80, I88 and I8! may be disconnected from the circuits controlled by the relays RI20, RI30 and RI40 and the terminals IN to I85, inclusive, connectedto the terminals 68I to 885, respectively.

With the apparatus of Fig. 6 connected in the manner just explained, if a connection is routed by way of the line It through the finder switch I4 to the connector switch of Figs. 2 and 3, the application of ground potential to the control conductor 20 resulting from the operation of the relays R288 and R238 causes the series connected windings of the relaysR8I0 and R880 to be energized. The circuit, including these windings. may be traced as extending byway of the grounded conductor 20, the conductor Ila,

the terminals I80 and 888, the winding of R630 and the upper winding of RGIII- to battery. The

- marginal relay R8I0 does not operate when this circuit is completed. The relay R830, however, operates to complete, at RASBI, an obvious circuit for energizing the slow-to-release relay R820. The relay R820, upon operating, prepares at RA822, a circuit for energizing the relay B800 and prepares, at RAGZI, a. holding circuit for the relay R8I0.

In the event the call as routed from the substation A over the line II and through the connector switch of Figs. 2 and 3 is not successfully completed, the back-bridgerelay R2'I0 does not operate and hence the booster battery control relays R290 and R285 are not caused to operate. Accordingly, the relay R8I0 remains in its restored position. During the release of the connection and when ground potential isremoved from the control conductors and Ila, the relay R830 restores to complete, at RA03I, the circuit for energizing the line switching relay R800. The relay R800, upon operating, completes, at RA80I and RA602, paths extending by way of RABII for impressing the negative potential of the 110 volt coin refund current source upon the line conductors of the calling line II. At RA003, the relay R800 prepares a multiple holding circuit for the relay R8I0. The magnet I01 provided at the calling substation now operates in the manner previously explained, by operating to cause the coin or coins deposited in the coin-receiving means of the substation to be refunded. Shortly following the operation of the relay R800, the, relay R820 restores to open, at RA022, the operating circuit for the relay R800 and to open, at RA82I, the prepared multiple holding circuit for the relay R6I0.

In the event the call as routed from the line .II through the finder switch I8 and the connector switch of Figs. 2 and 3, is successfully completed, the relays R290 and R285 function in the manner set forth above to, impress, for a short time interval, the potential of the booster battery source 29% upon the control conductor 200- The resulting increased current flow over the circuit including the upper winding of R6I0 and R630, is such that the relay R8I0 operates to complete, at RA8I2, an obvious holding circuit for itself. At RA8II, the relay R8I0 prepares paths for impressing the positive potential of the 110 volt coin collect current source upon the conductors of the calling line. Thereafter, and when the connection is released,the relays R630 and R600 cooperate to complete these paths so that the magnet I0! is caused to operate to perform a coin collecting operation. During the release "of the-apparatus shown in Fig. 6, the holding circuit for the relay ROI0 is interrupted, at RA603, in response to the restoration of the relay R600. Aside from the release of the relayR5I0, the other relays of Fig. 6 are caused to restore in the exact sequence described above.

Since the booster battery control relays R290 andR295 are caused to operate to cause the operation of the relay R8I0 in extending connections both to and from the operators posi- 

